Aspectos biogeográficos do caracol gigante africano (Achatina fulica) no município de Maringá - PR

Abstract

We present an empirical study performed in the city of Maringá, Paraná. The objective of the research is to evaluate the current spatial distribution of the mollusk Achatina fulica, exotic species, in the urban and rural areas of the municipality. In the urban environment, there are numerous records of its occurrence in the form of complaints made to the Health Surveillance sector of the Municipal Health Department from 2005 to 2015; in the rural area, the almost absence of complaints demanded that the distribution be evaluated from a sample survey by means of a questionnaire applied to residents. In order to characterize and explain the positive occurrence of the species, the following elements were evaluated: location in coordinates, temperature, humidity, insolation, altitude and vegetation cover. The methodological procedures were initiated by the recorded complaints to the Department of Health, between 2005 - 2015; the points for the application of the interviews were spatially defined, by means of a uniform sweep of the area, covering both the urban area and the rural area; in the sequence, the questionnaires were applied, evaluating the microclimatic conditions and other environmental and vegetative aspects in the places where the mollusk was recorded. The third step consisted in the collection of data recorded complaints, we define the points of interviews, questionnaires, evaluation of specific microclimatic conditions and environmental factors. The next step was the logistic regression, considering the elements collected in the field, to identify the environmental elements with a chance of favoring the existence of the African giant snail. Snail distribution maps were prepared according to the investigated occurrence. As a result, it was identified that, in the urban area, the giant African snail is present in the older neighborhoods, inside de city: Jardim Alvorada, Vila Morangueira, Zones 07, Zona 03 and Zone 05, Parque das Laranjeiras, Zone 06 and, the Grevíleas Park; these urban environments have trees such as Sibipiruna (Caesalpinia pluviosa) and Tipuana (Tipuana tipu) with well-developed arboreal specimens that promote shading corridors and favor the existence of the mollusk; also contributes, the empty urban lands devoid of constructions and paved areas, favoring the burial and the reproduction of the species. It was found that the species has no preference for the valley bottom, where the soil is more soaked and the most common vegetation is leucaena (Leucaena leucocephala) and castor bean (Ricinus communis). We have identified that the preference of the species in the urban area is for environments with urban agglomeration with exposed soil and plant cover composed by large trees. In rural areas, on the other hand, most of the occurrences of the snail are concentrated in the vicinity of the water courses, where it is common to find houses remaining from the oldest occupation in the region. It was possible to show that the species under study is not present in temporary crops, which have intense mechanization, soil plowing and compaction and biocide application. Thus, the species showed a preference for places close to the dwellings and sheds, installed in the rural area, because these environments have humid places, with shading and generate organic solid waste that meet the food needs of the African giant snail. The interviews indicated that in the urban zone and in the rural zone of the municipality of Maringá most of the interviewed people apply the procedures of manual contact of suitable form, whose purpose is to avoid the contamination by the helminth Angiostrongylus sp. However, the risk is not exempt, as there are people who have contact with the species without hand protection and in more than 50% of the homes there are rodents (rats), both in the urban and rural environment, being definitive hosts of the worm. The reproduction control of the exotic species should take into account seasonal campaigns in the summer, encouraging daily manual harvesting, especially in the years when the El Niño phenomenon occurs or were, for various climatic rhythm reasons, present increased rainfall and humidity and, in parallel, the complaints in the Health Department of Maringá increase